Magnetic cores



March 5, 1963 s. M. RUBENS 3,080,549

MAGNETIC CORES Filed March 25, 1957 FIGJ. 24 10.2.

I2 PRIOR ART 2 42 64 4s 35 & I6 If k 46 I 52A) 8 INVENIOR SIDNEY M. RUBENS ATTORNEYS United States Patent 3,080,549 MAGNETIC CORES Sidney M. Rubens, St. Paul, Minn assignor to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Filed Mar. 25, 1957, Ser. No. 648,091 Claims. (Cl. 340-174) This invention relates to metallic ribbon cores which are especially adaptable for the non-destructive sensing of the magnetic state thereof.

As .used herein, the term non-destructive sensing of the state of magnetic cores refers to the detection of the relative direction of remanent flux in a magnetic core without destroying or reversing such remanent flux. This is not to say, however, that the remanent flux in accordance with this invention is not changed at least temporarily during the non-destructive sensing thereof, since as will become apparent hereinafter, the temporary change in the remanent flux, whether in one direction or the other, provides the desired indicative output.

As the use of magnetic cores in digital computing machinery becomes increasingly popular, one desire of those attempting to increase the computational speeds of these machines is to obtain magnetic cores which may be nondestructively sensed. In'retaining recorded data, nondestructive sensing eliminates the restoration cycle usually required with static magnetic memories.

Generally in some digital machine applications magnetic material used in the cores preferably exhibits a red tangular hysteresis characteristic so that the residual flux density is a relatively large percentage of the flux density during application of a saturating magnetomotive force. A number of suitable magnetic materials are available such as Permalloy, and certain ferromagnetic ferrites. Permalloy is preferably used as thin insulated strips wrapped around the circumference of miniature spools thereby improving the high frequency response by reducing eddy current losses. Such cores are commonly referred to as metallic ribbon cores.

In non-destructively sensing the state of metallic ribhon cores, electrical current may be passed through the ribbon thereby inducing a magnetic field orthogonal to the remanent magnetization which causes sufficient disturbance in said remanent magnetization to induce a detectable voltage in a sense winding. This disturbance is insufiicient to switch the remanent magnetization of a core exhibiting a rectangular hysteresis loop provided the leads are brought out in such a manner that the net component of the magnetic field due to the leads is negligible along the length of the core. In a coiled core such component is generally referred to as the circumferential field and will be so referred to herein in a generic sense without limitation intended. The circumferential field phenomena are explained by D. A. Buck and W. 1. Frank in their article Non-Destructive Sensing of Magnetic Cores, Communications and Electronics, January 1954, on page 822.

One difficulty in this method of non-destructive sensing is keeping the net field due to the leads for the interrogating or sensing current close to zero. A field which may be sufiicient to switch the core may be generated by the interrogating current in the electrical lead attached to the innermost end of the ribbon.

This invention obviates the lead or circumferential field referred to above by providing a magnetic core which has both of the electrical terminals thereof on one side of a coil. In one preferred embodiment, this is accomplished by providing a length of ribbon-like material and folding same at substantially its mid-point. The folded length is then wrapped or coiled around a bobbin with the ends of the length being secured to terminal means ice disposed in the bobbin. Current is then provided to the terminal means so that the current will traverse the full length of the folded magnetic material to provide a quadrature flux for sensing the remanent flux in the length of mag netic material. The terminal means in their connection to the current so used extend from one end of the bobbin and cannot, therefore, produce circumferential or other adverse fields.

Accordingly, it is one object of this invention to provide an improved ribbon-like magnetic core suitable for non-destructive sensing.

Another object of this invention is to provide magnetic core non-destructive sensing apparatus wherein the ends of the ribbon-like material used for the core are disposed both on the same side of the coil forming the core.

Another object of this invention is to provide apparatus for non-destructive sensing of a coiled magnetic core including means for applying sensing current to the coiled core and invariably generating a net zero magnetic field 'along the circumference of the core.

Another 'object or this invention is to provide a magnetic core including a length of ribon-like material folded at substantially its mid-point so that the'halves' thereof are lying adjacent each other with the resultant halves being coiled, whereby 'the ends of the length are disposed on the inward side of the coil for connection there- 'to of means to cause a current'to fiow throughout the length of the material. A'fuifther object of this invention is the provision, in conjunction with'the precedingobject, of terminals"disposed in bobbin-like means for securing the ends of said length to the bobbin and for making the connectionto the current producing means.

Still other objects of this invention will become apparent to those of ordinary skill in the art by reference to the following detailed description of exemplary embodiments of the apparatus and the appended claims The various features of the exemplary embodiments according to the invention may be best understood with reference to the accompanying drawings, wherein:

FIGURE 1 illustrates in perspective view a ribbon core in accordance with the prior art;

FIGURE 2 illustrates a schematic and diagrammatic elevational view of the magnetic core in accordance with this invention;

FIGURE 3 is a side elevational view of the core of FIGURE 2 showing schematically the balance of fluxes therein produced, and

FIGURE 4 is a perspective view of a magnetic core showing the inward connection of the coiled core.

The priorart is shown in FIGURE 1 for convenience in explaining the operation of the present invention. The metallic ribbon type memory core of FIGURE 1 is shown in conventional coil form, but the usual bobbin associated therewith is not illustrated so that the operation of the core may be better described. To the outer end of the magnetic ribbon 10 is connected a conductor wire 12 for purposes of introducing current through the coiled length of the ribbon. At the other end v14 of the ribbon, which is inside the coil, other current leads are attached so as to cause current to exit on line 16. At the terminal end 14 of the ribbon, the lead line 16 is formed by two branches '18 and 20, one of which passes on one side of the coil and the other of which passes on the other side of the coil. These branches combine into' the external line 16.

Since the metallic ribbon used for the core has rectangular hysteresis loop characteristics, the core will have its remanent magnetization along an easy axis or direction of magnetization. The core is formed such that an easy axis is along the length thereof, and when current is'passed through the magnetizing winding 22 in the dispewin rsc snf arnqu 2 m s anent flux, s set uninth 9919...... -bluf p po e s i r. o h 31? x a d fo in the direction shown by vector 26. An output Winding similar type windings.

28 is used to determine the direction of the remanent As above indicated, the length of magnetic ribbon has magnetization in the corewhen sensing or interrogating two portions at least electrically interconnected. Throughurr i ausedtq flOW Fh QU h theilength of the core 5 out this specification and-in the claims, phrases similar itself. 'Ihatis, whencurrententersil-ine l zgandflexits to two portionsatleast electrically interconnected," as r u hlin L .t c putput winding hi. a. YQ1 f;2 tg6 .at'apo'int' 42,-:are-iintended to include both .the situation du ced .thereinwhich indicates the direction of wherethedengthis of a- -single strip folded and the':situanent magnetization. Current flowing in on linelz creates tion where two separatestrips are connected together to i i form the left-nail ;unless otherwise expressly stated. The remainder of the description will pr'oce'ed with reference to a folded strip-tor ribbont'or convenience in explaining I the invetl tibmjbut limitation thereto is not intended.

'Ueen" magnetizing the folded ribbon with current in .the n aagnetizing winding SOQ remanent fiux'is setup in l thefc'o're in a git/en directiomalong its folded length. lwh'en 'sns'irig' current is introduced, for example at terinalll thfe current 'flo'w's throughout the full length :Qfthe bon andexits through the opposite terminal '46. IIhe'sensii i'g current produces a qundrzitureflux, and as iifthe p or art, tends to rotate theremanentj fiux" into 1 therewith; The tangential change in the remanf voltagein the sens ingwinding in on e direction or the otherfin accordance with the direction of the remanent flux to produce}: "signal indicative er the state of'th magnetic core; "Even though sensing current the magneticjribbon' inoppod to rotate the remanent" flux I trons, thereifis f no cancellation plained; the output winding sees'only th'ftan'gential directiorn GURE 3 "whichfi's a view of the enter ng lean-54 so as to cause a quadrature flux in "4.0, ',t he[fli1x" produced by leadf54 is as shown by l 56 "fUponcomplete traversal of Ithe"current other no prob1 m arises V r r l e i g 40, 115 line 31'6- inl e r maa ioitf s tnc sfiii e. nigh ime ate afl t v' h as. hatby vector Since. the it lf cmntnavetsg53 mqmismglhjslight same eurr'ent'fiows in'line 54as does in line 58, the flux g n g h lead; 13mm" go i vectors" '56 and 60 will be of the same magnitude, and able ghangeeinuth ni n ijfi h miim-n I they are in opposite directions, will completely can'- tween these 1eads eachlother. ThCl'fOrC, 16 net circumferential flux tial fi ld ffii i t magnitudeetq 1 3 inthe tended to be produced thereby is negligible if not compre f. an interrogating vquadmmm; fi l may, be :pletely absent. Differences in the resistances of the leadnL Si i i d imbl' 6 im th t bf fif in and lead-out connectors 54 and 58 are not ascritical as magnetic core without switching thecore, the fcircuinferf the Mi branchmembsrs and 20 of G R ential fields so produced areobjectionable Anoth FIGURE 4 shows m greater detail a metallic ribbon Problem, aside {mm the critical a fi lfi q .Of -the magneticcore in accordance with this invention. The leads audio, is that m leads p e -"3 hb terminals 46 and 48 of the length of the folded ribbon of t in e th o d th f Thi 'i is to FIGURE 2 are secured to the bobbin by any desirable adverse loadingeegects. means, such as shown in FIGURE 2 diagrammatically i m'id as i g a mfignylm ml by the elements 62 and 64 which are inserted into the in FIGURE 2; ver t e; de p d sf 'fm 5m bobbin In FIGURE 4, the securing elements 62 and 64 f gm magnetic w h'f y blnolkd'esfmw are shown as U- shaped pieces which are crirnped or emtively sensed, a length of metaHicIibbonAO-Eis made into P'if 5 and of the bobbfn as as two portions of substantially equal length 'Thisimay b n thecylrndrieal central portion of the bobb1n. Theends accomplished by toldingvthe length at approximately its 46 and 48 of the core material are Welded or otherwise mid-Point; l n y, .fl ctrically eonn etihg two connected tothe securing'elements fiz and 64, respectively, strips f magmatic m' f approximatly u l g so as to allow a tight wind of the ribbon about the bobbin. g e o ff ir s'uch a point 4'z The elements 62 and 64 are preferably electrical conducwelding or other suitable means. With the two strips or F and a d m at one end of the bb folded 1ength;.portions adjacentjeach "otherend 55 ad i n, i These leads may heme S b y melamin length i w app d, around abd bi a P We s 1 or n 4 a n h h i-m e M 348 tivelyy'may "be welded'or otherwise electrically secured of the:-full,length=next enemas. i-Pref erabl y; as will e e o. Ihaarrangemem Of the leads 1S Sunder other be my discussed, the arenas and tenement; dia r m a y Shown in FIGURE Therefore; ameter of the bobbin. However,:it.isto.be understood flll m t -19 by v 'e i ii q lfiads d s sta that the te in ji e ds-- may di l' t ny Q ih versel'y afiect the magnetic core. It be noted that position 'aroundthebobbin'; .A's ananemasv i he fi lded r nt through t cpnu t ngcd uc r 64 eto current than may ti t ifli bdbb nith th s and: im il d v w w a i s m fi l i mm- 8jfih l t sbi sid ,o hecoi 5A a ne iz t. Q lF= fli fl 5 R7 ,Howeter, m? -W in: ll-and nu rgum n psiflxnayb added tqt mania sall l a l fit.i ls filt it llgf l.--? i 1 E 9 posing circumferential flux indicated by vector 76. These two circumferential fluxes will completely balance each other so as to provide a zero net circumferential tlux.

As above indicated, the disposition of the ends of the coil of magnetic material is preferably on a diameter of a bobbin in the manner illustrated in FIGURES 2 and 4. In this case, the two portions of the folded length of magnetic material will be different in length by an amount approximately equal to one-half the circumference of the bobbin. However, it is not essential that the terminals of the magnetic core be disposed on a diameter, but may be adjacent each other at any angle around the bobbin without there being and adverse magnetic or electrical effects produced.

Thus it is apparent that there is provided by this invention systems in which the various phases, objects, and advantages herein set forth are successfully achieved.

Modifications of this invention not described herein will become apparent to those of ordinary skill in the art after reading this disclosure. that the matter contained in the foregoing description and the accompanying drawings be interpreted as illustrative and not limitative, the scope of the invention being defined in the appended claims.

What is claimed is:

l. A magnetic memory core circuit comprising first and second juxtaposed pieces of magnetic material both having rectangular hysteresis loop characteristics and remanence in the same direction, at least one winding disposed about both pieces, and means for elfecting in said winding a signal indicative of the direction of remanence in the magnetic material including means for passing equal electric current simultaneously through the first and sec ond pieces in opposite directions, both of which are substantially parallel to said same direction.

2. A circuit as in claim 1 wherein said means includes an electrical interconnection between the pieces at one end thereof and terminals at the other ends thereof for connection to a source, whereby a single current from the source provides the equal and opposite current in the pieces.

3. A magnetic core comprising a coiled length of ribhon-like material having rectangular hysteresis loop characteristics, said length having two electrically interconnected portions of substantially equal lengths overlyingly adjacent each other substantially throughout said coiled length with each of said portions as coiled separating adjacent turns of the other, both said coiled portions having remanent flux in the same direction, and means connected at opposite ends of said length for passing current through said length, the arrangement being such that said current produces a flux at an angle to the remanent flux of said material.

4. Apparatus as in claim 3 wherein the flux produced by said current has at least in effect only a quadrature relationship with the remanent flux of said material.

5. Magnetic core nondestructive sensing apparatus comprising a core in the form of a length of ribbon-1ike magnetic material having first and second portions substantially equal in length and ovcrlyingly adjacent each other, one end of the first portion being electrically interconnected with an adjacent terminal end of the second portion and thereby forming a series electrical circuit through the extent of said first and second overlying portions respectively, said portions having a remanent flux in the same direction, means for passing current serially through the extent of the first and second adjacent overlyingly arranged portions with the current flowing in opposite directions through the first and second portions respective ly for producing a sensing flux at an angle to said remanent flux to cause a change in the remanent flux, and means to detect at least a portion of said change.

6. Apparatus as in claim 5 wherein the sensing flux is produced effectively only in a quadrature relationship Therefore, it is intended d with said remanent fiux and the change caused thereby is a reversible change.

7. Apparatus as in claim 5 wherein said two ribbonlike portions are coiled with each portion separating adjacent turns of the other portion and wherein the sensing flux producing means includes means for passing a current through said length.

8. A system as in claim 7 wherein the other end of each said portion forms one of two terminal ends of said length and are inside the coil.

9. Apparatus as in claim 7 wherein the other ends of said portions are on the inner circumference of the coil.

10. Magnetic core nondestructive sensing apparatus comprising a length of ribbon-like magnetic material having rectangular hysteresis loop characteristics and forming a magnetic core, said length having first and second serially arranged portions, said portions being electrically connected along one of the mutually adjacent terminal end points, said portions being of substantially equal lengths and disposed in overlyingly adjacent relationship to each other in coil form with the turns of each portion separating adjacent turns of the other portion, means for creating a remanent flux in the same direction along each of said portions, means for passing a current serially through the length of said first and second portions respectively with the current flowing in opposite directions through adjacent turns of said first and second portions to produce a sensing flux at an angle to said remanent fiux to cause the remanent flux to align therewith, by means to direct a change of remanent flux along the length of said material.

11. Apparatus as in claim 10 wherein the current passing means produces said sensing flux effectively in only a quadrature relationship with said remanent flux.

12. Apparatus as in claim 10 wherein said two portions of ribbon-like material are coiled around bobbin-like means including terminal means for securing thereto both ends of said length of magnetic material, said terminal means being connected to the means for passing current through the length of said material and being disposed transversely of said length.

13. Apparatus as in claim 12 wherein the terminal means are diametrically opposed in said bobbin-like means.

14. Apparatus as in claim 12 wherein the terminal means extend from the same end of the bobbin-like means.

15. A magnetic core comprising ribbon-like ferromagnetic material having rectangular hysteresis loop characteristics and being in the form of a strip returned back on itself and providing two portions of substantially equal lengths lying adjacent and parallel to each other, said returned strip having a remanent magnetization axis along the length thereof and being of coil form.

References Cited in the file of this patent UNITED STATES PATENTS 2,278,744 Sparrow Apr. 7, 1942 2,723,353 Spitzer et al. Nov. 8, 1955 2,743,507 Kornei May 1, 1956 2,814,794 Bauer Nov. 26, 1957 2,982,947 Kilburn et a1. May 2, 1961 FOREIGN PATENTS 1,105,870 France July 13, 1955 OTHER REFERENCES A New Nondestructive Read for Magnetic Cores," by R. Thorenson and W. R. Arsenault, 1955 Western Joint Computer Conference, published August 1955, pp. 111- 116. (Copy in Div. 42.)

Non-destructive Sensing of Magnetic Cores," by D. A. Buck and W. I. Frank in Communications and Electronics for January 1955, pp. 822-830. (A copy is in the Patent Oflice Library.) 

1. A MAGNETIC MEMORY CORE CIRCUIT COMPRISING FIRST AND SECOND JUXTAPOSED PIECES OF MAGNETIC MATERIAL BOTH HAVING RECTANGULAR HYSTERESIS LOOP CHARACTERISTICS AND REMANENCE IN THE SAME DIRECTION, AT LEAST ONE WINDING DISPOSED ABOUT BOTH PIECES, AND MEANS FOR EFFECTING IN SAID WINDING A SIGNAL INDICATIVE OF THE DIRECTION OF REMANENCE IN THE MAGNETIC MATERIAL INCLUDING MEANS FOR PASSING EQUAL 